Definition The mitral valve consists of small leaflets of tissue that separate the heart's left atrium, which receives blood from the lungs, and left ventricle, which pumps blood to the rest of the body. Mitral valve prolapse is a condition in which the mitral valve balloons back into the left atrium when the heart pumps. About 3% to 5% of the population has mitral valve prolapse. Women are affected more often than men.
What is going on in the body? Usually the mitral valve remains firm when the left ventricle contracts. For reasons that are not clear, the tissues that make up the valve sometimes thicken, weaken, and degenerate. When that occurs, the valve balloons back into the left atrium when the left ventricle pumps. This sometimes allows blood to leak backward. This is a condition known as chronic mitral regurgitation. Mitral valve prolapse is generally not serious. In older men, the cords around the mitral valve can rupture and cause more severe leakage.
What are the signs and symptoms of the condition? Most people with mitral valve prolapse have no symptoms at all. The condition is usually found during a regular physical examination. Those who do have symptoms may have the following:
palpitations or a heightened awareness of the heartbeat
What are the causes and risks of the condition? The cause of mitral valve prolapse is unknown. It is more common in people with low body weight and low blood pressure. It is also more common in those with a hollow at the lower part of the breastbone, called pectus excavatum or funnel chest. People with mitral valve prolapse may face a slightly increased risk of stroke, heart attack, and sudden death, though this is controversial.
What can be done to prevent the condition? There are no known ways to prevent this condition.
How is the condition diagnosed? Mitral valve prolapse is usually diagnosed in the course of a physical examination. The doctor, using a stethoscope, may hear the abnormal valve click halfway through the heartbeat. This click may be followed by a murmur that goes with chronic mitral regurgitation. The doctor can make the click and murmur occur earlier in the heartbeat by having the person stand or tighten his muscles as if having a bowel movement. An echocardiogram, a special imaging test of the heart using sound waves, can show a thickened valve that balloons into the left atrium can confirm the diagnosis if needed by visualising the abnormal valve and can show blood flowing backwards through the valve into the left atrium.
What are the long-term effects of the condition? Mitral valve prolapse can progress with time to the point where mitral regurgitation occurs or worsens. This rarely means that the valve must be replaced. Some experts believe that vigorous exercise can make mitral valve prolapse worsen faster, though this has not been proven. This is mainly because men develop mitral regurgitation more than women do. Some people with mitral valve prolapse have rapid or irregular heart rhythms that they feel as palpitations.
What are the risks to others? There are no direct risks to others. Mitral valve prolapse seems to run in families.
What are the treatments for the condition? In most cases, no treatment is needed. The person needs to be reassured that this condition is not serious. If a person has mitral regurgitation as well as mitral valve prolapse, antibiotics, such as amoxicillin, need to be given during various medical and dental procedures. This reduces the risk of getting an infected mitral valve. For those who develop rapid or irregular heartbeats, a class of drugs known as beta-blockers may be given. Examples of these drugs include metoprolol or atenolol. Also, these persons should avoid dehydration and limit caffeine intake.
What are the side effects of the treatments? Side effects depend on what treatments are used. Antibiotics can cause rash, diarrhoea, and other side effects. Beta-blockers can cause slow heart rates, low blood pressure, depression, sexual problems such as erectile dysfunction, and unpleasant dreams.
What happens after treatment for the condition? Many symptoms may go away after the person is reassured that mitral valve prolapse is not serious.
How is the condition monitored? Regular physical examinations are usually enough to check for the development of mitral regurgitation. Echocardiograms may be used to check the seriousness of the mitral regurgitation.
Author: William M. Boggs, MD Reviewer: HealthAnswers Australia Medical Review Panel Editor: Dr David Taylor, Chief Medical Officer HealthAnswers Australia Last Updated: 1/10/2001 Contributors Potential conflict of interest information for reviewers available on request
